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Results & Discussion
Across groups, participants slept an average of 6.73
hours (SD = 0.56). Only one participant slept an
average of 8 hours or longer.
•Average sleep onset latency was 12.31 minutes
(SD = 8.15)
•Average sleep efficiency was 83.65% (SD = 6.29)
•Average minutes of wake after sleep onset (WASO)
was 67.67 (SD = 30.32)
We ran a series of general linear models to compare
phone usage (3 groups; Night Shift, regular, and no
phone) on sleep onset latency, total sleep time, sleep
efficiency, and WASO.
There was no statistically significant effect of
condition on sleep onset latency, total sleep time,
sleep efficiency, and WASO.
•This may be partially attributable to our participants
being chronically sleep restricted
In chronically sleep
adults, phone use
before bed (regardless
of use of iPhone Night
Shift) does not impact
167 emerging adults (ages 18-25; Mean age =
20.85, SD = 2.13, 65.8% female) who owned and
used an iPhone daily participated in this study
Participants were excluded based on diagnosed
sleep disorders and irregular sleep schedules
Participants were randomized into one of the
following conditions for seven nights:
•No phone for one hour prior to bed (N = 60)
•Regular phone use for one hour prior to bed
(N = 51)
•Phone use with Night Shift feature turned on for
one hour prior to bed (N = 56)
Participants’ sleep was tracked with a wrist-worn
Actigraph GT3x+ and phone use was tracked with
the Moment application
Human circadian rhythms are highly dependent on
light/dark cycles (Mein et al., 2014)
Light exposure from electronic devices can delay
sleep onset and circadian rhythm (Chang et al.,
Blue wave light is most likely to create alertness
• Apple’s iPhone has created the Night Shift
feature to reduce blue wave light exposure
•No studies have examined the effects of Night
Shift usage on sleep outcomes
Ninety-five percent of college students own a
smartphone (Pew, 2017), and the majority of
college students are not obtaining adequate sleep
(Campsen & Buboldz, 2017)
Aim: Examine potential differences in sleep
outcomes using iPhone Night Shift compared to
two control conditions (light exposure with no Night
Shift, no light exposure)
Hypothesis: Participants using Night Shift before
bed will demonstrate superior sleep outcomes
compared to phone use without Night Shift, but
poorer sleep outcomes compared to no phone use
Does iPhone Night Shift Improve Sleep Latency and Sleep Quality
In Emerging Adults?
Kara McRae Duraccio, Ph.D., Kelsey K. Zaugg, & Chad D. Jensen, Ph.D.
Total Sleep Time